Targetoid hemosiderotic nevus (THN) appears as a slightly elevated melanocytic nevus surrounded by a peripheral pigmented targtoid halo, which has a predilection for the trunk. The development of the ring may be sudden without any known traumatic even...
Targetoid hemosiderotic nevus (THN) appears as a slightly elevated melanocytic nevus surrounded by a peripheral pigmented targtoid halo, which has a predilection for the trunk. The development of the ring may be sudden without any known traumatic event, and the ecchymotic halo often regresses. A 17-year-old female was presented with an asymptomatic 5mm-sized, brown-colored macule on left breast for 10 years, which developed a sudden violaceous halo and enlargement. The patient had no history of trauma on the lesion. Histopathological examination revealed the intradermal, melanocytic component, which had symmetrical, well-circumscribed melanocytes arranged in uniform nests intermingled with dilated vascular spaces and red blood cells extravasation. As most THN spontaneously regresses, the patient was instructed to re-examine after one year. The clinicians should consider a diagnosis of THN when observing a sudden change in color or size of the pre-existing melanocytic nevus regardless of any traumatic event. Its favored location on the trunk might be prone to repeated mild traumas leading to the development of THN. By using dermoscopy, clinicians can avoid unnecessary procedures as THN is a clinical simulator of clinically worrisome malignant transformation.